Hydraulic brake level indicator



1950 n. SEBASTIAN ,EI'AL 3 ,38

HYDRAULIC BRAKE LEVEL INDICATOR Filed NOV. 10, 1948 DAVID SEBASTIAN ROBERT H-HAMPTON 'BERNT J. HEGGEN INVENTORS ATTORNEY Patented Dec. 19, 1980 HYDRAULIC BRAKE LEVEL INDICATOR David Sebastian, Robert H. Hampton, and Bernt J. Heggen, Kings County, N. Y.

Application November 10, 1948, Serial No. 59,394

1 Claim. (Cl. 177-311) This invention relates to an electric liquid level indicator for hydraulic brakes arranged to give a warning when the level of the liquid used for operating the hydraulic brakes drops below a danger point. An electric light or an electric bell may be used to show the danger point of the level of the liquid.

An object of this invention is to provide a self-contained plug which is designed to be inserted in the master cylinder in which the brake operating liquid is to be maintained at a set level, the plug having an electrode insertable in the container for the liquid with the lower surface thereof immersed in the liquid, the plug body having a. diaphragm and an electric contact cantrally thereof, and to provide means for energizing the electromagnet, the device being arranged so that when the level of the liquid is sui'ilcient thediaphragm contact is on an electromagnet, thereby breaking the light or bell circuit.

Another object of this invention is to make the diaphragm of resilient metal and constructed so that it will due to its inherent resiliency rise into contact with an adjustable member in circuit with a grounded electric light or bell and so that when the level of the liquid is below the electrode. the electromagnet circuit is broken and the light or bell circuit is closed causing the light or hell signal to give warning of the low oil condition.

With the above and other objects in view, the invention will be hereinafter more particularly described, andthe combination and arrangement of parts will be shown in the accompanying drawings and pointed out in the claim which forms part of this specification.

Reference will now be had to the drawings,

' wherein like numerals of reference designate correspondingv parts throughout the several views, in which:

Figure l is a front elevation of the electric P 18.

Figure 2 is a central cross-sectional view. the section being taken on line 2-4 in Figure 1 and showing the electric plug mounted in a master cylinder oi a hydraulic brake.

Figure 3 is a top plan view of the plug body with the cover removed. and without the master cylinder shown in Figure 2.

In the illustrated embodiment of the invention. the numeral It indicates a self-contained electric signal operating plug comprising a casing l I having a centrally apertured threaded lower end portion I! for securing to a master cylinder II in which hydraulic brake operating liquid is to be maintained at a set level.

Secured in the threaded portion I2 is a sleeve I 4 made of insulating material and an electrode ii of a length to extend into the master cylinder i3 and be immersed at its lower end in the liquid therein.

The lower surface of the electrode I5 is raised above the lower surface of the master cylinder II. A skeleton disk-shaped resilient diaphragm I1 is mounted on the upper surface of the casing II. The diaphragm I! has a plurality of radial arms l8, at the junction of which is a contact is which faces the upper end portion 20 of the electrode IS. The contact is is normally in contacting relation with the electrode l5.

Secured to the casing II by a thread 22 is a plastic cover 23 having a threaded boss 24 centrally thereof. Mounted in the boss 24 is a threaded adjusting member 25, the lower end oi which is normally out of contact with the diaphragm ii. The diaphragm is insulated from the casing H by an annular washer 26 made of insulating material and placed between the diaphragm and the casing.

An electromagnet 28 is mounted in concealed relation in the casing il in circumscribing relation with the upper portion of the electrode II and insulated from the casing by suitable insu-- lating material 2..

when the user fllls the liquid above the danger level and the electrode is immersed in the liquid. the electromagnet becomes energized, thereby moving the armature contact to the electromagnet and breaking the circuit to a signal lamp or to the electric bell.

The drawing shows the liquid at the safe full level. The armature contact is on the electrode and has broken the circuit to the signal lamp or to the electric bell.

An air vent 30 is in the electrode is and communicates with the atmosphere through a passage II in the casing l I. The air vent allows air to pass through the easing into the master cylinder It as the liquid is drawn out therefrom.

In operation. when the level of the liquid drops below the electrode I5, the current flow through the electrode is stopped. This demagnetizes the electromagnet and releases the diaphragm. The diaphragm contact moves up and contacts the adjusting member. The current is now flowing through the signal light or electric bell.

The function of the concealed diaphragm and contact member and concealed electromagnet is to prevent exposure of these parts to inclement weather conditions.

It is to be noted that the resilient diaphragm is constructed so as to rise into contact with the adjusting member 25 unless pulled down by the electromagnet 28 when magnetized.

As shown in Figure 2, it will be seen that a grounded battery 21 is connected to contact terminal 33. From the terminal 33 is a connecting wire 34 suitably connected to the electromagnet 28 and a connecting wire 3| suitably connected to the diaphragm or armature II. It will also be seen that a grounded electric light 38 is connected to the adjusting member 2! and that current from the battery 32 passes through the connecting wire 85, through the diaphragm armature i1, contact I! and through the adjusting member 25 to the electric light 38 when the liquid level drops below the electrode ll.

when the liquid level is as shown in the drawing, the current from the battery 32 passes through the connecting wire 34, through the electromagnet 28, through a connecting wire 31 from the electromagnet to the electrode i5, and through the liquid in the grounded master cylinder l3.

It is to be noted that while we have shown the electromagnet housed in a self-contained plug, that we may mount the electromagnet and armature on the dashboard of a vehicle to which the apparatus herewith disclosed is particularly of the invention as defined by the appended claim. 40 2,161,441

We claim:

In a hydraulic brake system, comprising a metallic receptacle or master cylinder for holding an electrically conductive hydraulic brake oil for said system, an electric plug secured to said cylinder and having an insulated metallic electrode, said electrode having its lower end immersed in said liquid and electrically connected with said cylinder by said liquid, an insulated and concealed electromagnet circumscribing the upper portion of said electrode, a resilient and concealed armature mounted in said casing and having a contact at its lower face and in contacting relation with the upper face of said electrode, a circuit comprising said electrode and a source of current, electrical indicating means in said circuit, an air passage in said casing, an air vent passage in said electrode and communicating with said air passage in said casing, said air passages permitting air to pass through said casing into said cylinder, whereby when the level of said conducting liquid drops below the lower surface of said electrode, said circuit is broken, causing said electromagnet to be deenergized to permit said resilient diaphragm'to move up into contacting relation with said signal circuit to produce an alarm.

DAVID SEBASTIAN. ROBERT H. HAMPTON. BERNT J. HEGGEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 838,823 Thomson Dec. 18, 1906 1,818,185 Yull Aug. 11, 1931 Vickers June 6, 1939 

